Long-term memory consolidation depends on proteasome activity in the crab Chasmagnathus

Long-term memory formation depends on protein and mRNA synthesis that subserves synaptic reorganization. The removal of pre-existing inhibitory proteins by the ubiquitin-proteasome system (UPS) is proposed as a crucial step to support these modifications. The activation of the constitutive transcription factor nuclear factor kappa B (NF-kappa B) depends on the degradation of the inhibitor of NF-kappa B (I kappa B) by the UPS. Here we study the effect of a UPS inhibitor, MG132, on long-term memory consolidation and NF-kappa B activation in the learning paradigm of the crab Chasmagnathus, a model in which this transcription factor plays a key role. Here we found that administration of MG132 interferes with long-term memory but not with short-term memory, and no facilitatory effects were found. Then we studied the effect of the UPS inhibitor on NF-kappa B pathway, finding that MG132 blocks the activation of NF-kappa B induced by training. These results suggest that the UPS is necessary for long-term memory consolidation, allowing for the activation of NF-kappa B as one of the target molecular pathways. (c) 2007 IBRO. Published by Elsevier Ltd. All rights reserved.